GB2176089A - Feed product and process for producing same - Google Patents

Abstract

A food product is provided, such as crouton, which will withstand hot or cold liquids for a prolonged period without losing its crispness. Croutons are produced by mixing ingredients such as flour, bran, starch, fat and flavourings, feeding the mix to cooker extruder (2), extruding cooked mix via nozzles (9), aperture (13), expansion chamber (14), apertured plate (18), expansive chamber (17) and nozzle (16) to a cutter and then cooling the cut croutons. Apertures (19) in plate (18) are preferably 1-1.5mm diameter and the nozzle is preferably 15mm diameter and the cooker produces croutons of uniform structure. <IMAGE>

Description

SPECIFICATION Food product and process for producing same This invention relates to a food product and a process for producing same. The invention has been conceived in relation to the production of a crouton and will thus be discussed primarily in relation thereto but the invention has a wider application.

At present, croutons are produced on a commercial scale by preparing a generally conventional bread mix or dough and baking it in relatively thin layers or generally cylindrical rolls and then cutting the layers into cubes or the rolls into discs. The cubed crouton typically has a side or edge dimension of 6mm - 13mum and the discs a diameter of about 18mm - 25mm and a thickness of about 6mm. After being cut, the baked pieces are then deep fat fried and often subsequently coated with a flavouring. Alternatively, the flavouring can be added to the basic mix before baking. In all cases, conventional croutons have an alveolate structure on all sides in the case of cubes and at least on the two major opposed faces in the case of discs.

Two main disadvantages of croutons produced by the normal baking process as described are that they have a relatively high fat content, typically in the region of 40% by weight, and can only be used as a table top addition to soup because if they remain in hot soup for more than a few minutes, they become soggy and disintegrate which is a very undesirable characteristic. The reason why the crouton becomes soggy and disintegrates is that the frying step in the manufacturing process merely coats the cellular structure with fat which stays intact when cold but which melts at around 35"C when placed in hot soup (typically at 60-80DC) and is thus replaced by the soup or other liquid the water content of which soaks into the cells making them soggy leading to disintegration.

The more traditional baking process is employed because it is not possible using known techniques to produce a food product of a cross-sectional area required for croutons, for example, by an extrusion cooking process. This is because if one attempts to extrude say a 2.5 cms diameter cylinder using a cooker extruder the centre of the cylinder is at least blown through due to the operating pressure within the cooker and at worst, the food product is disintegrated into powder or granular form by this operating pressure.

It is a primary object of the present invention to produce a food product using a cooker extruder and having a relatively large cross-sectional area, and a secondary object is to produce a crouton which essentially will not become soggy and disintegrate when placed in a hot liquid such as soup irrespective of the period of time to which it is subjected to that liquid.

According to a first aspect of the present invention there is provided a process for producing a food product comprising the steps of preparing a mixture of the desired ingredients, feeding the mixture to a cooker extruder, extruding the cooked mixture through a die head comprising at least one composite die, cutting the food product issuing from the die head into the required size and shape, and cooling the cut food product, whereby a food product of relatively large cross-sectional area and of substantially uniform structure is provided.

The process may include the further step of coating the cut food product with a flavouring which may be savoury or sweet, depending on the nature of the product being manufactured. This coating step may be carried out after cutting but before cooling, or after cooling. The advantage of coating after cooling is that the basic food product may be stored and then coated with the desired flavouring as and when required. The process may include the further step of toasting or frying the cut food product prior to cooling, this step being in addition to, or instead of, the coating step.

According to a second aspect of the present invention, there is provided a food product produced according to the process of the first aspect of the invention.

The food product preferably comprises a mixture containing, by weight, 40% to 95% amylaceous powder with the balance selected from 0% to 60% fibre-containing material, 0% to 15% texture modifier, 0% to 8% fatty substance, 0% to 5% of flavours and/or flavour enhancers, and 0% to 20% proteinaceous substance.

One formulation producing a good textured, palatable crouton has the following approximate composition by weight.

Wheat Flour 40.5% Oat Bran 50.0% AMIOCA (TM) Starch 5.0% Vegetable Oil 2.4% Sugar 1.5% Salt 0.5% The cross-sectional shape of the food product may be varied by changing the shape of the exit aperture in the or each composite die. Cross-sectional shapes which have been produced include circular, oval, rectangular (including square) and trapezoidal. Food products having a diameter or width of up to 2.5 cms have been produced by the process according to the first aspect of the invention, which products have a substantially uniform texture throughout which has not been possible heretofore using cooker extruders in view of the problem of blowing through or fragmentation referred to above.

In order to produce a crouton with an exposed alveolate structure which is expected of a soup crouton, the fat content is increased because this prevents the cut surfaces sealing over which they do with a reduced fat content. However, this is merely a matter of presentation and does not affect the ability of a crouton produced in accordance with the present invention to withstand hot liquids, such as soup, without becoming soggy and disintegrating. This characteristic of the crouton is believed to be due to the fact that, using the process of the present invention, the fatty substance (be it by way of an added ingredient or part of the natural content of one or more other ingredients) in the mixture is an integral part of the structure of the food product as opposed merely to a coating as in the conventional baked crouton.Thus the fat does not melt, thereby protecting the structure from attack by water, when subjected to hot liquids such as soup. This is a very significant advance in the art. For example, it allows restaurants and the like to place croutons in a soup and serve the crouton-laden soup as a combination, thus avoiding the need to serve the croutons separately and yet not having to worry about the possibility of the croutons becoming soggy.

In one experiment, croutons produced in accordance with the present invention were boiled in water for two hours without any impairment of the crispness thereof.

According to a third aspect of the present invention, there is provided a composite extrusion die for a cooker extruder, the die comprising a diffuser having an inlet for receiving, in use, a product issuing from a cooking region of the cooker extruder, an outlet through which the extruded product issues, and apertured means disposed intermediate the inlet and outlet and through which the food product passes in moving through the die from the inlet to the outlet The apertured means may comprise one or more plates each formed with one or more apertures of a relatively small cross-sectional area compared with that of the die outlet. If circular apertures are employed, a typical diameter would be of the order of 1 mm to 1.5 mm compared with that of the outlet of about 15 mm.

It is not fully understood why the apertured means overcomes the problems of blow through and fragmentation but is is thought that it serves to effect a pressure drop in the cooked mixture to an extent which prevents that pressure being released quickly through the only available port in known arrangements, namely the die outlet, hence disturbing the food product being extruded therethrough to the extent of blowing through the centre thereof and destroying the homogeneity, or actualiy breaking down the product into a powder or granuies as already mentioned.

A plurality of plates may be used in series each with the same or different aperture pattern and sizes.

Afood product produced in accordance with the present invention exhibits a remarkable degree of homogeneity and thus represents another significant advance in the art.

A food product and a process for producing same in accordance with the present invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 is a schematic side view of a cooker extruder used to produce a food product in accordance with the present invention.

Figure 2 is an enlarged section of part of Figure land Figures 3 and 4 are plan views of alternative components of Figure 3.

Referring first to Figure 1, the cooker extruder illustrated is basically of conventional form such as the Twin Screw Cooker Extruder Model No.BC45 produced by Creusot Loire, a French company of Firminy-Chazeau, France. The cooker comprises a pair of intermeshing rotary feed screws 1 located in a substantially cylindrical casing 2. An extrusion nozzle with die means 3 (or die head) is provided at an outlet end of the casing 2 and an inlet for the food mix is provided by way of a hopper 4 generally at the other end of the casing. Between the inlet hopper 4 and the extrusion nozzle 3 three regions of processing are defined within the casing 2. Immediately succeeding the inlet hopper 4 is a region 5 wherein the food is mixed thoroughly by the flights of the screws 1.Next is a region 6 wherein pressure is progressively applied to the food by gradually decreasing the volume of that portion of the casing 2 in relation to the volume of food mix therein.

The temperature of the food mix is thereby raised and it is possible to reach temperatures sufficient to cook the food mix, although additional heat may be applied if necessary by heating the exterior of that portion of the casing which comprises the cooking region. Finally, the pressure applied to the food is reduced and moisture in the food mix which was raised above the boiling point of water during cooking to allow some of it to flash off, if desired.

Referring to Figure 2 and looking more specifically at the die head, which has been modified in accordance with one aspect of the present invention, this comprises a conventional collector ring 7 which provides a chamber 8 in which the cooked food mix issuing from nozzles 9 associated with the respective screws 1 is collected together before issuing through a central aperture 11 in that ring to a diffuser ring 12 having a central inlet aperture 13 aligned with the collector outlet 11 which opens into a chamber 14. A nozzle 15 is connected to the diffuser ring 12 and has a central outlet 16 to which the cooked food product is directed, the nozzle having a chamber 17 which complements the chamber 14 of the diffuser ring. Thus as the cooked food mix passes through the die head 3, it is first constrained to pass from the collector ring 7 to the diffuser ring 12, then allowed to expand in the chamber 14, 17 and then finally constrained as it is extruded through the outlet nozzle or aperture 16.

Between the diffuser inlet 13 and the final outlet nozzle 16 there is provided, in the diffuser ring 12, an apertured plate 18. In Figure 2, the plate 18 is shown as having four apertures 19 equispaced around a circumference inset from the periphery of the plate 18. The plate 18 is also shown as having a central, generally conical extension 21 extending towards the diffuser inlet 13. This extension 21 serves to guide the cooked food mix towards the apertures 19. In some instances, if the extension or guide 21 is not provided, food mix can build up centrally of the upstream face of the plate 18 and harden, if not burn, with the possibility of particles thereof becoming loosened and then blocking one or more of the apertures 19.

Figures 3 and 4 show alternative plates 18 with different patterns of apertures: Figure 3 shows an increase in number of apertures 19 and Figure 4 shows the use oftwo rings of apertures. The diffuser ring 12 may be extended axially towards the die head 3 so as to accommodate a plurality of plates 18. The use of a multiplicity of plates 18 and the number and arrangement of the apertures 19 therein depends on the type of food mix being handled and the operating conditions of the cooker extruder. The plates 18 have to withstand a relatively high pressure, of the order of 2000 psi (146.2 kg/cm2), and thus need to be correspondingly robust. A thickness of 10 mm has been found satisfactory with apertures 19 of 1 mm to 1.5 mm in diameter in conjunction with a nozzle 16 of 15 mm diameter.

The nozzle 16 may be of any desired cross-sectional shape so as to shape the extruded food product accordingly. As the food product is extruded through the nozzle 16 as a continuous piece, a conventional rotary knife (not shown) cuts it into individual pieces of the required size. If a nozzle 16 of circular cross-section is employed, the knife 22 cuts the resulting extruded cylinder basically into discs but because some subsequent expansion of the food product takes place, the discs take a final form which is generally that of a flying saucer which is found to be attractive both visually and from the standpoint of being placed in the mouth for eating.

Where the food product is primarily intended for a snack food, salad accompaniment, or the like, it is preferably manufactured so as to have a generally sealed outer surface, irrespective of its shape. This "sealing" is in fact a function of the fat content in the original mix, the lower the fat content, the better the "sealing" which takes place when the product is cut by the knife 22. The non-cut surface or surfaces of the product tend to be relatively smooth or sealed by virtue of having been in contact with the nozzle 16. The "sealing" referred to is in fact a flowing of the food product which is still hot and thus plastic when cut and if the fat content is increased, this flowing is inhibited, thus producing an alveolate cut surface which is normally required (by customer demand) for a soup crouton.

The production by extrusion cooking -of a food product of a relatively large cross-sectional area but having a substantially uniform structure lends itself to the manufacture of a variety of sweet or savoury food products the nature and texture of which is governed by the ingredients in the basic mix and the operating conditions of the cooker extruder. The basic flavouring of the food product, be it sweet or savoury, may be effected by including one or more appropriate ingredients in the food mix.

This flavour coating may be applied as part of the original manufacturing process or the unflavoured food product stored and then flavoured on demand. After flavouring, if required at one stage or another, the food product may be toasted, deep fat fried, or otherwise treated as required before finally cooling which may in some instances be preceded by a drying step.

The following are examples of mixtures which are suitable for producing a snack crouton in accordance with the process of the present invention, all pecentages being by weight, and the mixtures falling with the overall formulation of: Amylaceous powder 40% - 95% Fibre-containing material 50% - 60% Texture modifier 0% - 15% Fatty substance 0% - 8% Flavours and Flavour enhancers 0%- 5% Proteinaceous material 0% - 25% Example 1 Wheat Flour 40.5% Oat Bran 50% AMIOCA(TM) Starch 5% Vegetable Oil 2.5% Sugar 1.5% Salt 0.5% Example 2 Wheat Flour 40% Oat Bran 50% AMIOCA (TM) Starch 6.5% Vegetable Oil 2.5% Sugar 1.5% Salt 0.5% Example 3 Wheat Flour 60% Oat Bran 25% AMIOCA (TM) Starch 8% Vegetable Oil 5% Sugar 1.5% Salt 0.5% Example 4 Wheat Flour 41% Oat Bran 50% AMIOCA (TM) Starch 6.5% Vegetable Oil 2.5% Example 5 Wheat Flour 25% Oat Bran 60% AMIOCA (TM) Starch 15% Example 6 Wheat Flour 96% GMS 2% Sugar 1.5% Salt 0.5% Example 7 Wheat Flour 63% Oat Bran 10% Vegetable Oil 2% Proteins 25% If a soup crouton is required with an alveolate suface structure, then the fat content in the above seven examples can be increased up to the desired maximum of 8% with a corresponding decrease in one or more of the other ingredients.

The precise form of the basic ingredients can be varied with examples of possible alternatives being as follows: Amylaceous Powder- Wheat flour, rice flour, barley flour, rye flour, soya flour.

Fibre-containing material Oat bran, wheat bran, soya bran, maize bran, seed husks, dehydrated fruit pulp, spent grains from fermentation processes, fibre of extracted vegetable origin.

Texture Modifier - AMIOCA starch, amylopectin, a starch complexing agent, such as glyceryl mono stearate (GSM).

Fatty Substances - Vegetable oil, hardened vegetable oil, animal fats.

Flavours and flavour enhancers - Sugar, salt, monosodium glutamate (MSG), ribotide, spices, herbs.

Proteinaceous Material - Casein, gluten, sodium caseinate, calcium caseinate, soya isolate.

Example 1 above has been used to produce a very satisfactory "sealed" crouton in terms of texture, appearance and palatability with the cooker extruder operating at about 2500 psi (182.75 kg/cm2) producing a cooking temperature of about 170"C with a water content of 13-14%. The food mix has an equilibrium moisture content which may be increased, if desired, by injecting water into the cooker extruder prior to the cooking zone. The croutons produced in this way exhibit remarkable resistance to water absorption and thus remain crisp even when immersed in hot soup or other liquids. The croutons are preferably deep fat fried after being cut and then heat dried at 1 00'C for approximately 15 minutes. The subsequent application of a flavour coating may be effected as described, the flavouring being of spices, cheese, meat flavours for savoury products, and fruit flavours, for example, for sweet products.

The fat content in the croutons produced according to Example 1 is of the order of 25% which is considerably lower than that of conventional croutons and yet can still withstand immersion in hot liquids.

Thus the present invention enables an homogeneous food product of relatively large cross-sectional area to be produced by the extrusion cooking process which has not been possible heretofore and products such as croutons can be produced which retain their crispness even after prolonged exposure to hot liquids.

Claims (19)

1. A process for producing a food product comprising the steps of preparing a mixture of the desired ingredients, feeding the mixture to a cooker extruder, extruding the cooked mixture through a die head comprising at least one composite die, cutting the food product issuing from the die head into the required size and shape, and cooling the cut food product, whereby a food product of relatively large cross-sectional area and of substantially uniform structure is provided.

2. A process according to claim 1, and including the further step of coating the cut food product with a flavourant.

3. A process according to claim 2, wherein the coating step is carried out prior to the cooling step.

4. A process according to claim 2, wherein the coating step is carried out after the cooling step.

5. A process according to any of the preceding claims and including the further step of toasting the cut food product prior to the cooling step.

6. A process according to any of claims 1 to 4 and including the further step of frying the cut food product prior to the cooling step.

7. Afood product produced according to the process of any of the preceding claims.

8. A food product according to claim 7 and comprising a mixture containing, by weight, 40% to 95% amylaceous powder with the balance selected from 0% - 60% fibre containing material 0% - 15% texture modifier 0% - 8% fatty substance 0% - 5% flavours and/or flavour enhancers 0% - 20% proteinaceous substance

9. A food product according to claim 8, wherein the mixture is in accordance with any of Examples 1 to 7 substantially as herein particularly described.

10. A food product according to claim 8, wherein the amylaceous powder is selected from wheat flour, rice flour, barley flour, rye flour and soya flour; the fibre containing material is selected from oat bran, wheat bran, soya bran, maize bran, seed husks, dehydrated fruit pulp, spent grains from fermentation processes and fibre of extracted vegetable origin; the texture modifier is selected from AMIOCA starch, amylopectin and a starch complexing agent such as glyceryl mono stearate; the fatty substance is selected from vegetable oil, hardened vegetable oil and animal fats; the flavours and/or flavour enhancers are selected from sugar, salt, monosodium glutomate, ribotide, spices and herbs; and the proteinaceous material is selected from casein, gluten, sodium caseinate, calcium caseinate and soya isolate.

11. A composite extrusion die for a cooker extruder, the die comprising a diffuser having an inlet for receiving, in use, a product issuing from a cooking region of the cooker extruder, an outlet through which the extruded product issues, and apertured means disposed intermediate the inlet and outlet and through which the food product passes in moving through the die from the inlet to the outlet.

12. A die according to claim 11, wherein the apertured means comprises at least one plate, the or each plate being formed with one or more apertures of a relatively small cross-sectional area compared with that of the die outlet.

13. A die according to claim 12, wherein the or each aperture in at least one plate is circular and has a diameter of the order of 1 mm to 1.5mm compared to a diameter of the order of 15mm for the die outlet.

14. A die according to claim 12 or 13, wherein the plate is provided with a plurality of holes arranged on a circle.

15. A die according to claim 12 or 13, wherein the plate is provided with two sets of a plurality of apertures, each set being arranged on a circle.

16. A die according to any of claims 11 to 15, wherein at least one plate has an extension of the inlet face which serves to spread the food product towards the or each aperture.

17. A composite die for a cooker extruder substantially as herein particularly described with reference to Figures 1 and 2 or as modified by Figure 3 or Figure 4.

18. A cooker extruder having a composite die according to any of claims 11 to 17.

19. A process for producing a food product substantially as herein particularly described.